Coffee Club VOLUME 55 Exploring Coffee Vintages
Specialty coffee and freshness have always been hot topics. Whether it's the amount of time off-roast a coffee has been rested or how fresh the green coffee is before it was roasted, it's the main element that defines the entire ethos of specialty coffee. But what if we could find a way to STOP coffee aging!?!? This month, we dive into freezing green coffee and vintages of coffee with a 2022 vintage red bourbon from Burundi Bukeye that's been frozen and preserved at peak freshness right after harvest. And we pair that with the fresh crop SL 34/ SL 28 Kenya Kianderi.
What is a coffee vintage?
Like the commonly used concept in wine, the word vintage refers to the year the coffee was harvested, picked, and processed. A given year's weather patterns—the amount of rain received, the range of temperatures, and how the coffee was processed post-harvest, for example—can significantly affect the quality and quantity of the green coffee from that year's harvest. A vintage of a coffee offers a snapshot of that coffee at that specific point in time.
So...how does freezing green coffee work?
Once a coffee is picked, its degrading process slowly starts. Because green coffee is hygroscopic, it absorbs moisture easily, so keeping it dry and cool is essential. Freezing green coffee is one of the newer ways the specialty coffee industry has researched and found to preserve peak freshness in green coffee. Dr. Christopher Hendon, an assistant professor at the Department of Chemistry and Biochemistry at the University of Oregon, has conducted extensive research on the impact of temperature on coffee quality and extraction. He found, "For every 10ºC you cool something down, most of the processes occurring in the bean occur at half the rate." This provides a solid scientific basis for the benefits of freezing green coffee.
It supports the idea that freezing coffee prevents chemical reactions that occur over time (like stalling or aging) by making them proceed exceptionally slowly. Ultimately, the key element to freezing green coffee is that the moisture within the coffee bean itself is condensed and, therefore, can not escape from the beans. Due to the temperature level, all microbial activity inside the beans slows by more than half the usual rate or stops entirely.
Why do we do it?
Generally, most specialty coffee roasters consider green coffee fresh for six to 12 months after harvested. Once the year mark has passed and the following year's coffee harvest is processed, shipped and landed, the coffee is considered a 'past crop'. This label is generally associated with an aged and unfresh flavour profile, as the coffee has lost some of its original characteristics over time. However, this timeframe can change, and freshness varies widely depending on the exact coffee origin, variety, how it has been processed, and its overall quality level.
Freezing green coffee helps preserve these characteristics and slow the process of deterioration. It is also a valuable tool for farmers to reference past crops and compare coffee year to year.
❄️ Frozen Factoids ❄️
Bukeye
This Red Bourbon lot is produced by 322 farmers who deliver freshly picked coffee cherries to the Bukeye Washing Station. Gaharo Hill is significant because it is where the Long Miles Project began. The first washing station was built on land cleared by local farmers, using bricks made from clay found in the nearby valley. These farmers still deliver their coffee cherries to Bukeye to this day.
Kianderi
About 760 smallholder farmers grow this SL 28 and SL 34 coffee near Wambu in Murang’a County, central Kenya. They are part of the New Weithaga Cooperative Society. The farmers planted their coffee trees in the early 1950s on the slopes of Mt. Kenya and the Aberdare Ranges.
About the Coffees: Roaster's Notes 📝
Burundi Bukeye
Burundi's harvest season typically begins in April, and by the end of June, the last of Burundi's cherries arrive at the washing station. Each farmer's contribution to the washing station is recorded using Long Miles's farmer card system, which ensures that the best quality of cherry can be traced back to the farmer who grew it at hill level.
The cherries are floated and hand-sorted for peak ripeness and are then pulped to undergo a single fermentation process. The coffee in parchment spends around twelve hours dry fermenting. The parchment is sometimes 'footed' - a team of people will agitate and dance on the slippery coffee parchment by foot, helping to loosen any remaining mucilage clinging to it. It is then rinsed in fresh water, graded by density and left to soak for another four to six hours in the final rinse tank. The parchment is pre-dried for six to forty-eight hours, during which it is handpicked for under- or over-ripeness, insect damage and visual defects. It is then moved to African raised tables, where it slowly dries until it reaches a desired 10.5% moisture level.
The only other time we ever roast a frozen green coffee is for our Best of Box, and our approach tends to remain the same. We allow the cooled coffee to thaw for a good three days for it to reach thermal equilibrium. The coffee usually receives a longer soak in the roaster before we ramp up the heat. We prefer a slower roast to allow the thermal energy to penetrate the inside of the bean and cook it evenly. In the cup, we taste dark berries, dried fruits like apricots and dates, red tea, and a lovely citrusy finish.
Kenya Kianderi
We were introduced to Kianderi in 2023, and immediately upon cupping it, we knew it to be a special lot. What made it so special was the flavour depth and perfect acidity. Kianderi Coffee Factory is located in Kirinyaga, which lies beneath the slopes of the usually overcast seventeen thousand-plus foot Mount Kenya looming above. The nutrient-rich, deep red-orange volcanic soil is surrounded by lush, green, densely populated indigenous trees, and it plays a massive role in giving the coffee its particular blend of sweetness, complexity, and perfect balance of acidity and body.
The Kirinyaga area experiences a biennial production cycle, with the early harvest from April to June and the late second season from October to December. After harvesting, the cherries are delivered to the factory and are pulped immediately. The pulped coffee is stored overnight in fermentation tanks and dried on raised tables the next day.
Our roasting approach towards most East African coffees is to roast quick and end with a lighter temperature to allow the terroir to shine through. For this coffee, we wanted thermal momentum to build up during the drying phase and then carry through the rest of the roast as we steadily decreased our heat application. In the cup, the acidity shines in the form of blackberries, cranberries and red plums; a thicker, more viscous mouthfeel comes through in the form of ripe, purple grapes and violets. The overall experience is crisp, tart and lively.
Be sure to join us next month for Coffee Club Volume 66, a highlight on women producers from Bolivia. See ya soon!! 👋